flows: fix FlowNonApplicableException and EmptyFlowException leading to infinite spinners

passbook/core/templates/error/embedded.html

@@ -0,0 +1,25 @@
+{# Template used by bad_request_message within flows #}
+{% extends 'login/base.html' %}
+
+{% load static %}
+{% load i18n %}
+{% load passbook_utils %}
+
+{% block title %}
+{% trans card_title %}
+{% endblock %}
+
+{% block card_title %}
+{% trans card_title %}
+{% endblock %}
+
+{% block card %}
+<form method="POST" class="pf-c-form">
+    {% if message %}
+    <h3>{% trans message %}</h3>
+    {% endif %}
+    {% if 'back' in request.GET %}
+    <a href="{% back %}" class="btn btn-primary btn-block btn-lg">{% trans 'Back' %}</a>
+    {% endif %}
+</form>
+{% endblock %}

passbook/flows/exceptions.py

@@ -2,8 +2,8 @@
 
 
 class FlowNonApplicableException(BaseException):
-    """Exception raised when a Flow does not apply to a user."""
+    """Flow does not apply to current user (denied by policy)."""
 
 
 class EmptyFlowException(BaseException):
-    """Exception raised when a Flow Plan is empty"""
+    """Flow has no stages."""

passbook/flows/views.py

@@ -54,7 +54,10 @@ class FlowExecutorView(View):
                 LOGGER.debug("f(exec): Redirecting to next on fail")
                 return redirect(self.request.GET.get(NEXT_ARG_NAME))
         message = exc.__doc__ if exc.__doc__ else str(exc)
-        return bad_request_message(self.request, message)
+        return to_stage_response(
+            self.request,
+            bad_request_message(self.request, message, template="error/embedded.html"),
+        )
 
     def dispatch(self, request: HttpRequest, flow_slug: str) -> HttpResponse:
         # Early check if theres an active Plan for the current session

passbook/lib/views.py

@@ -27,12 +27,12 @@ class CreateAssignPermView(CreateView):
 
 
 def bad_request_message(
-    request: HttpRequest, message: str, title="Bad Request"
+    request: HttpRequest,
+    message: str,
+    title="Bad Request",
+    template="error/generic.html",
 ) -> TemplateResponse:
     """Return generic error page with message, with status code set to 400"""
     return TemplateResponse(
-        request,
+        request, template, {"message": message, "card_title": _(title)}, status=400,
-        "error/generic.html",
-        {"message": message, "card_title": _(title)},
-        status=400,
     )